This invention relates to coupling devices for removable coupling of a plumbing fitting, such as a plug that is inserted into and adjusted to seal non-threaded pipes used in plumbing systems.
It is known in the field of plumbing to install cleanout pipes in communication with a waste water pipe system so that objects lodged in the system may be removed through use of cables or other devices introduced into the system through the clean out pipe. Cleanout pipes are typically unthreaded and therefore must be capped at least during pressure testing of the waste water pipe system subsequent to installation. Preferably, the cleanout pipe is capped in a temporary manner so that access may be readily had without having to cut the pipe, as would be necessary for example, with a cap applied with adhesive.
Devices for plugging open-ended, non-threaded pipes are known to incorporate O-rings that seal against the inner wall of a pipe when compressed. Such devices, however, generally comprise a two-piece body in which a secondary clamping member is drawn upward or inward toward a primary clamping member by a relatively large screw or bolt to compress an O-ring seal positioned therebetween. The screw extends through apertures in both clamping members. These apertures must be sealed in addition to the seal already required at the gap between the device and the inner wall of the associated pipe. In addition, these devices generally require the use of a relatively large wrench to loosen or tighten the screw or bolt and generally cannot be installed using cordless screwdrivers which are becoming more prevalent in their use.
Such prior art seals rely solely on the compression of the seal against the inner surface of the pipe to hold the plug or other fitting in place. It is possible that during pressure testing of the plumbing system that the pressure in the line might be sufficient to blow such a plug out of the end of the pipe.
In addition, if it becomes necessary to seal the pipe at a position well within the bore rather than near the open end of the bore it may be possible to modify prior art devices to achieve this aim but according to the common prior art designs such a modification would require providing an elongated clamping member necessary to hold the shoulder and base elements together.
There remains a need for an improved coupling assembly for securing plugs and the like in the open end of a smooth walled pipe which is easy to install and forms an airtight seal between the inner wall of the pipe and the outer surface of the coupling assembly and which does not rely solely on the compression of the sealing means for securing the assembly in the open end of a pipe.